Motor drive control for wheelchair



' H. ROSENTHAL MOTOR DRIVE CONTROL FOR WHEELCHAIR Aug. 13, 1963 2Sheets-Sheet 1 Filed Oct. 9, 1958 Aug. 13, 1963 H. ROSENTHAL I3,100,860- I MOTOR DRIVE CONTROL FOR WHEELCHAIR Filed Oct. 9, 195a 2sheets-sheet 2 T0 BATTERY Unite Stats l at 3,100,860 I MOTOR DRIVEcoNTRoL non ELcrrAm 7 Harry Rosenthal, 6540 N. Campbell Ave, Chicago,lil- Filed Oct. 9, 1958, Ser. No. 766,294 4 Claims. (Cl. 318-55) forelectric driving apparatus used with such chairs.

Electrically driven wheelchairs for use by physically handicappedpersons have been known generally in the prior art and some have beenprovided with control means for driving the chair at different speeds inboth forward and reverse direction and for turning of the chair.However, the control apparatus for such chairs has generally been rathercomplex and involve the manipulation of a number of separate controlbuttons, dials or the like in order to turn or change the speed anddirection of movement of the chair. Since wheelchairs are often used bypersons whose manual dexterity and strength is serious- 1y limited,there is a definite need to provide control apparatus for such chairswhich are operable through a single easily manipulated control memberand which will, at the same time, be sufliciently versatile and flexibleto provide a high degree of maneuverability.

It is generally desirable that a motor driven wheelchair be providedwith two ranges of operating speeds; a higher speed for use outdoors anda lower speed for use indoors. While it is desirable that the chair beoperable at different speeds within each range, it is preferable thatcontrol means be provided such that a change from one range to the otheris not made inadvertently. At the same time, the provision for differentspeed ranges should be made without unduly complicating the controlmeans for the chair.

Accordingly, it is an object of the present invention to provide controlapparatus for a motorized wheelchair which controls are particularlyeasy to operate and adapted for use by partially disabled persons.

Another object of the invention is to provide a motorized' wheelchaireasily operable at different speeds and in different directions andwithin different speed ranges.

A further object of the invention is to provide an'electrically drivenwheelchair incorporating a single speed and direction control memberoperative on the so-called joystick principle and effective to controlboth the speed and the turning of the chair.

A feature of the present invention is the combination I of a pivotallymounted control element with a series of leaf-type switches to permitthe speed and direction of rotation of the wheels of an electricallydriven chair to be controlled separately by the progressiveincorporation of resistance elements to control the speed and directionof rotation of electric motors.

A further feature of the invention is the provision of a pair ofleaf-type switches connected to the field coil of a motor driving achair wheel with one of the switches in its normal orunactuatediposition providing a current path which cooperates with acurrent path through the other switch when the latter is in its actuatedposition to direct current through the iield coil in a predetermineddirection. With the first of the switches actuated and the second in itsnormal position, the switches cooperate to a form a current path throughthe field coil in the opposite direction to produce reverse rotation ofthe wheel.

Another feature of the invention is the provision of a double-throwswitch for incorporating or eliminating resistance elements into anelectric driving system'for a motorized wheelchair in order to providefor different speed ranges of operation for such chair.

3 1%,856 Patented Aug, 13, 1963 In the accompanying drawings:

FIG. 1 is a perspective view illustrating the general organization of anelectrically driven wheelchair utilizing the control means of thepresent invention;

FIG. 2'is a view in section taken through the top of the control boxused with the chair shown in FIG. 1;

FIG. 3 is a view in section taken on the line 33 of FIG. 2;

FIG. 4 is a view in section taken on the line 44 of FIG. 2;

FIG. 5 is a schematic diagram of the wiring circuit used for the controlmeans of the present invention; and

FIG. 6 is a schematic diagram of a portion of the wiring V circuitillustrating an alternative embodiment of the invention.

A motorized chair in accordance with the present invention includes apair of independently operated electric motors powered by a storagebattery and each arnanged to drive a wheel of the chair. Control of thedrive is accomplished through a pivotally mounted joy-stick member whichhas four leaf-type switches positioned around its axis and spaced apart.Operation of the joy-stick may progressively close the contacts of theleaf-type switches one or two at a time and in so doing connect thedriving motors to the battery and incorporate resistances of differentvalues into the circuit in order to control the current through thefield coils of the respective electric motors and thus control theirspeeds of rotation. A separate double pole, double throw switch may beprovided to incorporate separate additional resistances into the drivecircuits so that field coil current of a lower range is available thuspnoviding for drive at various lower speeds. When the range switch isset to its high speed position, the aforesaid independent resistancesare cut out'of the circuit permitting field coil current in a higherrange to flow for higher speeds of operation. A pair of the aforesaidleaf switches are connected in such a waythat when they are closed theyprovide a reverse current in the field coils of the respective motorsand permit backward movement of the chair. Because the joy-stick controlelement is operative in a 360 range it is possible to simultaneouslyforward drive one wheel while reverse driving the other thus permittingsharp turning of the chair. The control member thus consists of a singleelement which is easily controlled even by an incapacitated person whilepemnitting a relatively wide range of speeds to be' employed and makingthe chair highly maneuverable.

Referring now to the drawings, FIG. 1 is a perspective view of aninvalids wheelchair incorporating the present invention. The chair maybe of standard construction including a frame 10, a seat 12, baclr l4and footrests 15. The frame Ill is provided with main driving wheels 16and 17 being disposed on opposite sides of the frame, both wheels beingrotatably mounted on axles such as 18. Smaller front wheels 19 arepivotally secured to the frame to provide a stable balanced structure.Vertical frame members 21 and 22 extend upwardly from the lower framemembers 23 and 24 respectively and these vertical frame members serve tosupport the seat 12 and back 14-. Suitable handle grips 26 are providedso that the wheelchair may be conveniently moved by an attendant. Armrests 217 are also provided for the chair and supported by other membersof the frame.

The apparatus for propelling the wheelchair include reversible electricmotors 2'8 and 29 which are mounted on their respective support brackets31 and 32 disposed on the frame members 23 and 24. The motors 28 and 229include suitable gear reduction mechanisms which operate the drivingdrums 33 which are adapted to be moved into or out of engagementwith thewheels '16 and 17 through the operation of levers 34 and 36.

A standard 12 volt battery 37 is suitably supported beneath the seat ofthe chair and supplies current to the motors Z8 and Z9 andto the controlbox 39 which is connected to the motor through the cables 41 and 42.

The control box 3 9', as shown in FIGS. 2 and 3, contains a pair ofconnection boxes 43 and44 for the cables 41 and 42 respectively, and therheostats 46 and 47. A icy-stick type control member '48 is pivotallymounted in the top of the control box as more clearly shown in FIG.

4. Leaf switches 51, 5'2, 53 and 54 are mounted in the I bottom of thecontrol box 39 adjacent one end of the joy-stick'control member. As bestshown in FIG. 2-, the

leaf-type switches are arranged around the bottom of at its lower end. Aball 61 is disposed on the shaft 57 and is mounted between the socketwashers 62 and 63 so that a ball and socket connection is formed. Thisper- 4 contact with leaf 53d with flexible leaf 54c being carried intocontact with flexible leaf 54d. It will be evident that in thisconnection the arms 53b and 5412 are connected to an intermediate pointon the rheostats 46 and 47 so that the current through field coils 28aand 29a is increased and the speed of rotation of motors 28 and 29' andof the wheels 16 and 17 increases correspondingly. Still furthermovement, of the knob 58 to the forward position carries leaves 53d and54d into engagement with leaves 53c and S4e thus effectively shortingoutthe rheostats 46 and 47 andfurther increasing the speed of rotation ofthe wheels.

When the operator desires to move the chair backwards he pulls the knob53 toward him thus bringing the contact plate 59 against extension arms515a and 52x to move leaves 51b and 52b into contact with leaves 510 and520 respectively. In this position the switches 53 and 54 have theirrespective a and bleaves connected to one another thus providing currentpaths through those switches. It will be evident from FIG. 5 that inthis position connection is made to battery 37 so that l the directionof current flow through the field coils 28a mits the member 43 to bepivoted forward, backward, to

either side or to any intermediate position such as forward and to theleft or backward and to the right.

Each of the leaf switches numbered 51 through 54 (FIG. 5) includesflexibile contact arms which are designated by reference characters 51a,51b,'51c and 51d,

for example, on the reverse switch 51 and designated by referencecharacters 53a, 53b, 53c, 53d and 53e on the forward switch 53. Thus,forward switches 53 and 54 are provided with live leaves whereas thereverse switches 51 and 52 have but, four leaves. The leaf 51b has anextension portion designated 51x against which the contact plate 5 9 isadapted to bear on backward movement of the knob 58, while the leaf 53bhas a corresponding 7 extension 53x. The other switches 52 and 54 havecorresponding leaves and extending portions illustrated in the schematicdiagram of FIG. 5.

As indicated in FIG. 5, switches 51 and 54 control the motor 28 whichdrives the right wheel 16 of the chair while the switches 52 and 53control the motor 29 driving the left wheel 17. Switches 51 and 54 areconnected to the rheostat 47 while the switches 52 and 53 are connectedto rheostat 46. The double pole, double throw switch 56 provides forconnection ofrthe battery 37 to the field coils 28a and 29a of therespective motors.

In operation of the chair the arm 77 of switch 56 is moved to'connectthe centralcontacts 78 and 79 either to 'low speed contacts '81 and 82'or to the high speed contacts 8 3 and 84. Connection. to the low speedcontacts connects the variable resistors 66 and 67 into circuit so thata lower level of current is supplied to the field v coils 28a and 29athan is supplied when the high speed contacts 86 and 84 are connectedand the resistors are shorted out. a

Assume that the switch 56 is closed in the low speed position andthatthe operator wishes to move the chair straight forward at the lowestavailable speed. This is .accomplished by grasping the knob 58 andpushing it forward. This causes the ball 56 to pivot within the socketwashers and brings the contact plate 59 against the exten- 1 sions '5-3xand 54x thus moving flexible leaves 53b and 54b out of contact withleaves 53a and 54a respectively and into contact with leaves 530 and 54srespectively.

At the same time, switches 51 and 5 2 are in their normal positions sothat there are current carrying paths through closed contacts 51a, 51band 52a, 52b. This establishes a connection between the battery 37 andthe field colil 28a through the entire resistance of rheostat 47 andlikewise connects the battery to field coil 29a through the entireresistance of the rheostat 46 thus driving both wheels forward at thesame speed. As the knob 58 is moved further forward, flexible leaf 53cis pushed into and 29a will be the reverse of the direction in which thecurrent flows when the switches 53 and 54 were actuated. The connectionsmade include the rheostats 46 and 47 so that a controlled amount ofresistance is introduced into the circuit and the speed of rotation ofthe wheels 16 and 17 thus regulated. If it is desired to drive the chairbackward at a greater speed the knob 58 is moved further backward sothat flexible leaf 51(: contacts leaf 51d and leaf 52c contacts leaf52d. This provides connection to intermediate points on the rheo stats46 and 47 reducing their effective resistance and permitting higherspeed of rotation of the wheels.

Turning the chair is accomplished by moving the knob 58 in the directionin which the turn is to be made. For example, if a right turn is to bemadeimovement of the knob 58 to the right will cause the joy-stick mem-7 since this permits positioning of the contact member 59 so that itwill cause rotation of the wheels at diiferent rates of speed. For aless sharp tur-n knob 58 maybe moved forward and to the right so thatcontact member 59 closes switch 53 only with switch 51 remaining openand right wheel 16 remaining stationary. Also, switch 53 may be closedfurther than switch 54 for an even more gradual turn..

When it is desired to operate the chair at higher speeds, the arm 57 ofthe double throw, double pole switch 56 is moved against connections 83and 84 thus eifectively bypassing the resistors 66 and 67 and reducingthe total amount of resistance in the circuit. In this way, a higherspeed range is provided with adjustment within this range being made bythe position to which the knob 58 is moved. It is to be pointed out thata single throw switch may be used instead of the [double throw switch toprovide operation through a single range of speeds if desired. 7

The action of the joy-stick member '48 maybe made quite tree so thatrelatively little effort on the part of the operator is required to holdthe switches closed.

Although the particular arrangement illustrated shows a control systemand in which three forward speeds and two reverse speeds are shown foreach of the high and low speed ranges it will be understood that agreater or lesser number of different speeds may be provided simply bychanging the number of contacts on the leaf springs.

FIG. 6 illustrates an alternate speed control system providing twoforward speeds and two reverse speeds. The switches 152 and 153correspond rfunctionally to chair.

switches 52 and 53 respectively in FIG. and areconnected in circuit inthe same way as indicated by the reference characters and legends at theends of the brokenoffleads. Switches 152 and 153' are associated with apotentiometer 146 which provides apredetenmined speedcontrollingresistance. For low speed forward rotation of the left wheel of thechair, extension 153x is moved by the joy-stick and pushes leaf 153binto contact with leaf 153a so that the entire resistance ofpotentiometer 146 is in circuit; To increase forward speed, the operatormanipulates the joy-stick to :bring leaf 1530 against leaf 153d so thatonly a portion of the total potentiometer resistance (deter-mined 'bythe position of arm 146a) is connected. The position of arm 146a may becontrolled by means on the outside of control box 39 so that the maximumspeed maybe varied by the user to suit different conditions. Reversedriving speed is controlled in the same way through'switch 152. Acorresponding set of switches and potentiometer speed control isprovided for the right wheel.

The present invention provides, therefore, a simple and easily operatedcontrol for a motor driven wheel- By providing the combination of thejoy-stick control member and the leaf switches great flexibility ofspeed control is provided. Furthermore, since different wheels can berotated in different directions and diiferent speeds depending on thepositioning of the control knob, a chair equipped with such controlmeans is highly maneuverable and may be operated easily by a partiallyincapacitated person.

I claim:

:1. Electrical control means for a vehicle having on each of two sidesthereof a supporting wheel and a reversible electric motor for drivingthe same, with the wheel and motor on one side operating independentlyof the wheel and motor on the other side, said control means includingin combination, first and second circuits individually connected to themotors for energizing the same, a pair of leaf switches electricallyconnected in each circuit, the first switch of each pair having aplurality of flexible leaves including anintermediate leaf with one leafon one side thereof and atleast two leaves on the other side thereof,with the leaves being engaged in sequence by movement of saidintermediate leaf thereof to cause current fiow in the associatedcircuit in one direction to provide rotation of the corresponding motorand wheel in the forward direction, the second switch of each pair alsohaving a plurality of flexible leaves with an intermediate lea-f beingmovable to cause current fiow in the associated circuit in the oppositedirection to provide rotation of the corresponding motor and wheel inthe reverse direction, said first switches of said pairs beingoppositely disposed from said second switches thereof, and said switchesof one pair being positioned at right angles with respect to saidswitches of the other pair, a joy-stick control member pivotally mountedintermediate said first and second switches of both pairs forselectively moving said intermediate leaves thereof to operate saidswitches, whereby only'one "switch of each pair may be operated at agiven time, and resistor means connected to said leaves on said otherside of each of said first switches to introduce resistance into saidcircuit in one position of said first switches to control the currentflow in said circuits and thereby control the forward speed of themotors. i

2. Electrical control means for a vehicle having on each of two sidesthereof a supporting wheel and a reversible electric motor fordriving-the same, with the wheel and motor on one side operatingindependently of the wheel and motor on the other side, said controlmeans including in combination, first and second circuits individuallyconnected to the motors for energizing the same, a pair of leaf switcheselectrically connected in each'circuiL'the first switch of each pairhaving a pinrality of flexible leaves including an intermediate leafwith one leaf on one side thereof and at least two leaves on the otherside thereof, with the leaves being engaged in sequence by movement ofsaid intermediate leaf thereof to positions to cause current flow in theassociated circuit in one direction to cause rotation of thecorresponding motor and wheel in the forward direction, the secondswitch of each pair also having a plurality of flexible leaves and beingactuated by movement of an inter-mediate leaf thereof to cause currentflow in the associated circuit in the opposite direction to causerotation of the corresponding motor and wheel in the reverse direction,said first switch of each pair being oppositely disposed from saidsecond switch thereof, and said switches of said first pair beingpositioned at right angles with respect to said switches of said secondpair, a joy-stick control member pivotally mounted intermediate saidfirst and second switches of both pairs for selectively moving saidintermediate leaves thereof to opcrate said switches, whereby only oneswitch of each pair may be operated at a given time, resistor meansconnected to said leaves on said other side of said intermediate leaf ofeach of said first switches to introduce varying amounts of resistanceinto said circuit as said leaves on said other side of said firstswitches are engaged in sequence by progressive movement of saidcontrolmember to control the current flow in said circuit and therebycontrol the forward speed of the motor, and resistance means connectedin series with each pair of said leaf switches by means of a leaf ofeach of said first and second switches on the other side of saidintermediate leaf thereof for providing resistance in said circuitindependently of the position of said joystick control member.

3. Electrical control means for a vehicle having on each of two sidesthereof a supporting wheel and a reversible electric motor for drivingthe same, with the wheel and motor on one side operating independentlyof the wheel and motor on theother side, said control means including incombination, first and second circuits individually connected to themotors for energizing the same, a control box adapted to be mounted onthe vehicle, a joy-stick control device pivotally mounted on saidcontrol box with a knob extending above the control box and an actuatingmember within said box, a first pair of leaf switches connected in saidfirst circuit and disposed in said box on opposite sides of saidactuating member, and a second pair of leaf switches connected in saidsecond circuit and disposed in said box on opposite sides of saidactuating member, said switches of said second pair being positioned atright angles to said switches of said first pair, and each of saidswitches being angularly spaced about with respect to the adjacentswitch about said actuating member and at substantially forty-fivedegrees to the direction of movement of the vehicle, the first switch ofeach pair having a plurality of vfiexible leaves and being engaged insequence to cause current flow in the associated circuit in onedirection to cause rotation of the corresponding motor and wheel in theforward direction, the second switch of each pair having a plurality offlexible leaves and being operable to cause current flow in theassociated circuit in the opposite direction to cause rotation of thecorresponding motor and wheel in the reverse direction, said actuatingmember selectively engaging said switches to operate the same, each ofsaid circuits and said pair of switches connected thereto being arrangedto open the circuit and de-energize the associated motor in the eventthat both switches of said pair are simultaneously operated.

4. Electrical control means for a vehicle having on each of two sidesthereof a supporting wheel and a reversible electric motor for drivingthe same, with the wheel and motor on one side operating independentlyof the wheel and motor on the other side, said control means includingin combination, first and second circuits individually connected to themotors for energizing the same, a control box adapted to be mounted onthe vehicle, a joy-stick control device pivotally mounted on saidcontrol box with a knob extending above the control box and a roundactuating member within said box, a first pair of leaf switchesconnected in said firstcircuit and disposed in said box on oppositesides of said actuating member, a second pair of leaf switches connectedin said second circuit and disposed in said 'box on opposite sides ofsaid actuating member, said switches of said second pair beingpositioned at right angles to said switches of said first pair andeachof said switches being angularly spaced about 90 with respect to theadjacent switch about said actuating member, the first switch of eachpair having a plurality of flexible leaves including an intermediateleaf with one leaf on one side thereof and at least two leaves on theother side thereof, with the leaves on said other side being engaged inse quence by movement of said intermediate leaf thereof to positions tocause current fiow in the associatedcircuit in one direction to causerotation of the corresponding motor and wheel in the forward direction,the second switch of each pair having a plurality of flexible leaves andbeing actuated by movement of an intermediate leaf thereof to positionsto cause current flow in the associated circuit to cause rotation of thecorresponding motor and wheel in the reverse direction, said actuatingmember selectively moving said intermediate leaves of said switches: tooperate the same, each of said circuits and said pair of switchesconnected thereto operating to open the circuit and de-energize theassociated 'anotor when both switches of said pair are simultaneouslyoperated, and resistor means connected to said leaves on said other sideof said first switches to introduce resistance into said circuit in oneposition of said first switches to control the current flow in saidcircuits and thereby control the forward speed of the motors.

References Cited in the file of this patent UNITED STATES PATENTS

1. ELECTRICAL CONTROL MEANS FOR A VEHICLE HAVING ON EACH OF TWO SIDESTHEREOF A SUPPORTING WHEEL AND A REVERSIBLE ELECTRIC MOTOR FOR DRIVINGTHE SAME, WITH THE WHEEL AND MOTOR ON ONE SIDE OPERATING INDEPENDENTLYOF THE WHEEL AND MOTOR ON THE OTHER SIDE, SAID CONTROL MEANS INCLUDINGIN COMBINATION, FIRST AND SECOND CIRCUITS INDIVIDUALLY CONNECTED TO THEMOTORS FOR ENERGIZING THE SAME, A PAIR OF LEAF SWITCHES ELECTRICALLYCONNECTED IN EACH CIRCUIT, THE FIRST SWITCH OF EACH PAIR HAVING APLURALITY OF FLEXIBLE LEAVES INCLUDING AN INTERMEDIATE LEAF WITH ONELEAF ON ONE SIDE THEREOF AND AT LEAST TWO LEAVES ON THE OTHER SIDETHEREOF, WITH THE LEAVES BEING ENGAGED IN SEQUENCE BY MOVEMENT OF SAIDINTERMEDIATE LEAF THEREOF TO CAUSE CURRENT FLOW IN THE ASSOCIATEDCIRCUIT IN ONE DIRECTION TO PROVIDE ROTATION OF THE CORRESPONDING MOTORAND WHEEL IN THE FORWARD DIRECTION, THE SECOND SWITCH OF EACH PAIR ALSOHAVING A PLURALITY OF FLEXIBLE LEAVES WITH AN INTERMEDIATE LEAF BEINGMOVABLE TO CAUSE CURRENT FLOW IN THE ASSOCIATED CIRCUIT IN THE OPPOSITEDIRECTION TO PROVIDE ROTATION OF THE CORRESPONDING MOTOR AND WHEEL INTHE REVERSE DIRECTION, SAID FIRST SWITCHES OF SAID PAIRS BEINGOPPOSITELY DISPOSED FROM SAID SECOND SWITCHES THEREOF, AND SAID SWITCHESOF ONE PAIR BEING POSITIONED AT RIGHT ANGLES WITH RESPECT TO SAIDSWITCHES OF THE OTHER PAIR, A JOY-STICK CONTROL MEMBER PIVOTALLY MOUNTEDINTERMEDIATE SAID FIRST AND SECOND SWITCHES OF BOTH PAIRS FORSELECTIVELY MOVING SAID INTERMEDIATE LEAVES THEREOF TO OPERATE SAIDSWITCHES, WHEREBY ONLY ONE SWITCH OF EACH PAIR MAY BE OPERATED AT AGIVEN TIME, AND RESISTOR MEANS CONNECTED TO SAID LEAVES ON SAID OTHERSIDE OF EACH OF SAID FIRST SWITCHES TO INTRODUCE RESISTANCE INTO SAIDCIRCUIT IN ONE POSITION OF SAID FIRST SWITCHES TO CONTROL THE CURRENTFLOW IN SAID CIRCUITS AND THEREBY CONTROL THE FORWARD SPEED OF THEMOTORS.